페리틱 스테인레스 극박재의 성형한계도 도출 및 예측

Abstract

The forming limit diagram (FLD) of a 0.098mm-thick sheet of a ferritic stainless steel was determined using a modified Marciniak test. The Nakazima test was alsotried, but the test produced wrinkling on the sheet specimens and was thus unusable for the present material. The FLD was also theoretically predicted using amodification of the Parmar-Mellor-Chakrabarty (PMC) procedure, which incorporated the effect of surface roughness expressed in terms of the sheet thickness and the grain size. The ultra-fine grain size was determined by electron backscatter diffraction (ESBD). The prediction agreed well with experimental observation.